Abstract. A total of 577 visual surveys (each of 5 min in duration and 100 m2 in area) were conducted throughout 1990 and 1991 at 32 locations off four Canary ...
Marine Biology (1996) 125:215 231
9 Springer-Verlag 1996
J.M. Falcon' S.A. Bortone" A. Brito" C.M. Bundrick
Structure of and relationships within and between the littoral, rock-substrate fish communities off four islands in the Canarian Archipelago
Received: 23 May 1995/Accepted: 25 November 1995
Abstract A total of 577 visual surveys (each of 5 min in duration and 100 m 2 in area) were conducted throughout 1990 and 1991 at 32 locations off four Canary islands (i.e., Alegranza, Fuerteventura, Gran Canaria and Tenerife) with the objects of describing the coastal fish community, comparing the differences in the fish fauna within and between these islands, and determining the biotic and abiotic factors related to the structure of the fish communities. A total of 76 species were recorded; the most common were Abudefduf luridus,
Canthigaster rostrata, Chromis limbatus, Sparisoma cretense and Thalassoma pavo (94.28, 86.48, 52.34, 73.31, and 94.10% frequency of occurrence, respectively). The abundance and average size of the commercially important species was greater in those locations where there was less fishing pressure. The stepwise linear regression models were capable of explaining only a low amount of variation in the dependent variables (i.e., number of species, number of individuals, average size and species diversity) of the fish community. The independent variables recorded were date, time of day, depth, slope of the substrate, substrate type, percentage of sand, percentage of algae, algal height, number of sea urchins (Diadema antillarum) and the individual islands. An ANOVA, using the islands only as independent variables, indicated that each island contributed significantly to the variation in the four dependent variables
Communicated by A. Rodriguez, Puerto Real J. M. Falc6n (l~) "A. Brito Departamento de Biologia Animal (Ciencias Marinas), Facultad de Biologia, Universidad de La Laguna, E-38206 La Laguna, Tenerife, Canary Islands, Spain S.A. Bortone Department of Ecology and Evolutionary Biology, University of West Florida, Pensacola, Florida 32514, USA C.M. Bundrick Institute for Statistical and Mathematical Modeling, University of West Florida, Pensacola, Florida 32541, USA
and there were significant differences among the islands. Detrended correspondence analysis (DCA) and a two-way indicator species analysis (TWINSPAN) determined associations between species and environmental attributes of the survey locations. The patterns in the TWINSPAN analysis indicated that localities had faunal resemblances based on the island off which where they were located.
Introduction The Canarian Archipelago is located 100 and 450 km off the northwest African coast and is comprised of seven major islands and some minor islands (Fig. 1). The islands are volcanic in origin and have narrow continental shelves. Substrates in the littoral zone are principally composed of basalt and sand. Extensive sand bottom occurs off the easternmost islands. The environmental features of the waters surrounding the islands (mainly connected with the narrow continental shelves, direction of the dominant currents and winds, atmospheric conditions, proximity to the African continent, and low aquatic productivity) have led to the unique characteristics of their resident faunas (Brito 1984, 1991; Dooley et al. 1985). Within the Canaries, many species have a specific habitat affinity within the islands. For example, those species with warmerwater affinities occur predominantly in the western islands and those with more temperate-water affinities in the eastern islands. The first quantitative study of the inshore fish community was conducted by Bortone et al. (1991) off E1 Hierro. These investigators used visual-census data to describe the basic structural parameters (species richness, abundance, diversity, etc.). Subsequently, Bortone et al. (1992) compared the number, size, and biomass of parrotfish (Sparisoma cretense) between E1 Hierro and Fuerteventura. They found important differences in parrotfish population parameters between the islands,
216 a n d suggested t h a t these m i g h t be r e l a t e d to the differi n g degrees of t o u r i s m , d e v e l o p m e n t , a n d fishing pressure a s s o c i a t e d with each island. O t h e r q u a n t i t a t i v e studies o n the l i t t o r a l fish c o m m u n i t i e s of the i s l a n d s were c o n d u c t e d off A l e g r a n z a b y F a l c 6 n et al. (1993b). C o n t i n u i n g the studies i n i t i a t e d i n the a b o v e - m e n t i o n e d i n v e s t i g a t i o n s , o u r object in the p r e s e n t s t u d y was to a d d to the k n o w l e d g e of the s t r u c t u r e of l i t t o r a l fish c o m m u n i t i e s o n o t h e r C a n a r i a n islands. W e c o m p a r e v a r i o u s f i s h - c o m m u n i t y p a r a m e t e r s of the two most p o p u l o u s a n d developed islands ( G r a n C a n a r i a a n d Tenerife) with t h o s e of o t h e r i s l a n d s ( A l e g r a n z a a n d F u e r t e v e n t u r a ) w h i c h are less d e v e l o p e d a n d less m o d i f i e d b y h u m a n influence. W e also try to e x t e n d the i n f o r m a t i o n o n the r e l a t i o n s h i p s b e t w e e n b i o l o g i c a l v a r i a b l e s a n d a s s o c i a t e d e n v i r o n m e n t a l v a r i a b l e s , especially i n t h o s e b i o t o p e s w i t h a p r e d o m i n a n t l y r o c k substrate.
Material and methods Sampling locations Thirty-two localities were studied on the four islands (Fig. 1). The localities were selected for logistic accessibility and biotope. At each location the surveys sites were chosen to include a diversity of hard substratum and algal communities. Most of the surveys were conducted on a rock substratum, with occasional surveys on biotopes with a small percentage of sand within the census area. The samples were conducted in June 1990 on Fuerteventura, May 1991 on Alegranza, and in August 1991 on Gran Canaria. On Tenerife, the surveys were conducted between April 1990 and October 1991. A total of 577 surveys were made: 36 on Alegranza (a small, uninhabited island); 58 on Fuerteventura; 47 on Gran Canaria; and 436 on Tenerife.
Survey method Because of the high physical relief of the substrate, we followed the recommendation of Bohnsack and Bannerot (1986) and HarmelinVivien et al. (1985) and used a visual-census method. We followed the point-count, stationary visual-census method of Bortone et al. (1989), whereby the SCUBA diver/observer takes up position in the centre of an imaginary circle with a radius of 5.6 m (100 m2). The observer turns slowly within the circle for 5 rain, counting the number of individuals of each species and the size of each individual within the circle. The number of individuals was estimated for schooling species. Size (total length, TL) was estimated for each fish; to the nearest 1 cm for fish < 10 cm TL, and to the nearest 5 cm for fish > 10 cm TL. Some species of the family Mugilidae and the genus Seriola could not be identified to species and were recorded as Mugilidae and Seriola sp., respectively. Each was then treated as a distinct species in the analysis. All larvae were identified as such and also treated as a distinct species in the analysis. It should be noted that the taxon "larvae" probably represents several species. Abiotic and biotic independent variables were also recorded for each survey. Abiotic variables included date, time of day, depth, slope (numerically estimated from 1 = horizontal to 4 = vertical); four different types of substratum (1 = flat; 2 = low relief, < 1 m; 3 = high relief, between 1 and 3 m; and 4 = very high relief, > 3 m); and estimated percentage of the survey area covered by sand. Biotic variables included estimated percentage of the survey area covered by algae; height of the dominant algae; and numbers of the herbivorous sea urchin Diadema antillarum.
Data analysis The dependent variables chosen to describe the littoral fish communities were: number of species, number of individuals, and species diversity (Shannon-Weaver H', calculated according to Pielou 1966). Additionally, average size was obtained for each species during each survey. As the surveys were conducted in a 100 m z area, all survey parameters could be expressed in terms of the parameter per 100 m a.
Fig. 1 Map of Canary Islands and collection locations (1-32) surveyed during sampling period
Alegranza 9 Lanzarote~
30-ElVeril 32 31-LosJameos 3~'JP--30 32-PuertoV~ejo ~
CANARYISLANDS
~
24t..,ar 23 -\6q~ re
LaPalma
22_Jt~%~n~ 12
Tenerife
~ Fuerteventura
21r
-27
Gomera ~ ~ E I Hierro
f18"
~
1
7211~ 1-El Bajio 2-LasAguas 3-LasCaletiUas 4-LaCarrera 5-Puertitode G~Jimar 6-LaCaleta(PuntaGache) 7-Muellede [] Pods 8-El M(~dano 9-La Tejita 10-AguaDulce 11-LosAbrigos 12-Palm-Mar
117"
~
%'k.
ranCanaria
)-14
7~7@~ 1716 15 13-Pueriode Sardina 14-Playadel Cabrbn 15-Bajade PasitoBlanco 16-BaNa Arguineguin 17-Puntade PuertoRico 18-Playade los Armadores 19-MogAn 20=Puntade la Baja
de
=16"
115"
8~ 21-Ajuy 22-Los Molinos 23-Verildel Calamareo 24-BajOnde la Vieja 25-Los Becerros 26-Mue]lede Islade Lobes 27-,Jacomar 28-Las Playitas 29-Tarajalejo
f [ /" ] /A[ric ~
7* ii3~ m
114"
217 Regression models were constructed to explain the variation of the dependent variables attributable to the independent variables using stepwise, multiple linear-regression models. Furthermore, an ANOVA model was used, with the speci~c islands only as the independent variable, to determine if the islands significantly contributed to the variation in the dependent variables. Subsequently, Tukey's Studentized range (post-hoc) test was used to determine the statistical significance in the dependent variable recorded between island pairs. All these analyses were conducted with the SAS statistical program (SAS Institute Inc. 1985). To determine association patterns between species and localities, detrended correspondence analysis (i.e., DCA; DECORANA program: Hill 1979 a) and two-way indicator species analysis (TWINSPAN program: Hitl 1979 b) were used with the species-abundance matrix. The accepted level of significance was 0.05 in all analyses unless otherwise noted. In the TWINSPAN analyses, only those species observed in three or more surveys were retained in the analysis.
number of individuals per survey > 5.0) were: Abudefuf
Iuridus, Apogon imberbis, Atherina presbyter, Boops boops, Canthigaster rostrata, Chromis limbatus, Oblada melanura, SardineIla maderensis and Thalassoma pavo. The larval fish were also among the most abundant (17.07 individuals 100 m-2). In general, the variation in species abundance among the surveys was high, and the standard deviation was always higher than the average number of individuals per survey. Of all species recorded, the highest numbers of individuals recorded per survey ( > 500 individuals 100 m -2) were schoolrag, pelagic species (i.e., Atherina presbyter, B. boops, Sardina pilchardus, SardinelIa aurita and S. maderensis), some benthic and epibenthic species that formed loosely aggregated schools (i.e., Apogon imberbis, Chromis
limbatus, O. melanura, Pagellus acarne, Pomadasys incisus, Sarpa salpa and T. pavo), and unidentified larvae. Results
Descriptive statistics A summary of the descriptive statistics for the 577 surveys conducted at the localities is presented in Tables 1 to 3. A total of 76 species were observed, of which the most abundant (i.e., those with an average Table 1 Summary of species abundance (Mean 1 number of individuals per sample; Mean 2 number of individuals per number of samples in which species occurred; Max. maximum number of individuals per sample; %Occur. percent occurrence), average size (Av size), number of species, number of individuals, and species diversity recorded during sampling period (values in brackets minimum values recorded). Species'code numbers correspond to those in Fig. 2; some species of family Mugilidae and genus Seriola could not be identified, and were recorded as Mugilidae and Seriota sp., respectively; each was then treated as distinct species in the analysis
Code Species No.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32
Abudefdufluridus Apogon imberbis Atherina presbyter Aulostomus strigosus Balistes carolinensis Boops boops Bothus podas Canthigaster rostrata Centrolabrus trutta Chromis limbatus Corisjulis Dasyatis pastinaca Dentex 9ibbosus Diploduscervinus Diplodus puntazzo Diptodus sargus Diplodusvulgaris Echiichthys vipera Enchelyeore anatina Epinephelus aIexandrinus Epinephelus guaza Gobiuspaganellus Gymnothorax unicolor Heteroconger Iongissimus Heteropriacanthus cruentatus Kyphosus sectator Labrisomus nuchipinnis Lithognathus mormyrus Mugilidae (unidentified)
Mugil cephalus MuIlus surmuletus Muraena augusti
No species was present in all samples. When average abundance was calculated for only those surveys in which the various species occurred (Table 1), those species that dominated the abundance ranking were also those species that tended to occur in tightly organized schools or loosely aggregated groups. On the other hand, 25 species were never represented by more than 1 or 2 individuals in any survey. Species
Mean 1 21.332 9.088 19.861 0.029 0.001 27.178 0.159 5.254 1.469 87.637 0.428 0_006 0.005 0.259 0.008 2.128 1.149 0.006 0.001 0.001 0.017 0.015 0.003 0.242 0.103 0.008 0.064 0.010 0.003 0.008 0.830 0.013
(SD)
Max.
%Occur.
Mean 2
Av size
(28.29) (92.97) (123.43) (0.18) (0.04) (119.23) (0.59) (5.27) (2.44) (204.47) (2.08) (0.08) (0.09) (0.83) (0.10) (8.45) (4.04) (0.16) (0.04) (0.04) (0.14) (0.13) (0.05) (3.77)
301 1310 1000 2 1 1000 7 35 13 2000 36 1 2 7 2 102 48 4 1 1 2 2 1 80
94.28 10.57 4.33 2.60 0.17 16,46 9.87 86.48 41.07 52.34 13.69 0.69 0.34 13.69 0.69 14.90 20.97 0.17 0.17 0.17 1.56 1.38 0.34 0.69
22.62 85.96 458.40 1.13 1.00 165.07 1.61 6.07 3.57 167.44 3.12 1.00 1.50 1.89 1,25 14.27 5,47 4.00 1.00 1.00 1.11 1,12 1.00 35.00
8.16 2.81 5.46 51.76 20.00 13.12 12.90 5.11 9.91 8.48 7.72 50.00 41.66 19.25 21.00 16.15 15.31 8.00 70.00 10.00 38.00 5.88 75.00 50,00
(1.26) (0.20) (0.29) (0.13) (0.08) (0.20) (5.57) (0.11)
29 5 3 2 2 5 90 1
3.12 0.17 5.19 0.69 0.17 0.t7 10.05 1.38
3.33 5.00 1.23 1.50 2.00 5.00 8.25 1.00
21.66 20.00 12.02 19.16 40.00 30.00 18.96 61.87
(continued overleaf)
218 Table 1 (continued)
Code Species No. 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76
Mycteroperca rubra Myliobatis aquila Myrichthys pardalis ObIadamelanura Ophioblenniusatlanticus PageIlus acarne Pagrus auriga Pagrus pagrus Parablennius pilicornis Parapristipoma octolineatum Pomadasys incisus Pseudocaranx dentex Pseudolepidaplois scrofa Sarda sarda Sardina piIchardus Sardinella aurita Sardinella maderensis Sarpa salpa Sciaena umbra Scorpaena maderensis Scorpaena notata Scorpaena poreus Scorpaena scrofa Seriolafasciata Seriola rivoliana Seriola sp. Serranus atricauda Serranus cabrilla Serranus scriba Sparisoma cretense Sphoeroides spengleri Sphyraena viridensis Spondyliosoma cantharus Stephanolepis hispidus Synodus saurus Synodus synodus Thalassoma pavo Torpedo marmorata Trachinus draco Tripterygion delaisi Umbrina canariensis Vanneaugobius canariensis Xyrichthys novacala Unidentified larvae
No. of species No. of individuals Species diversity
with the highest frequency of occurrence were similar to those identified as frequently occurring by Bortone et al. (1991) in an earlier study conducted at E1 Hierro. In our study, the species with the highest frequency of occurrence were, in decreasing order of importance: Abudefdufluridus (in 94.28% of the total 577 surveys), Thalassoma pavo (94.10%) Canthigaster rostrata (86.48%), Sparisoma cretense (73.31%), and Chromis limbatus (52.34%). Among localities, the average number of species per survey lay between 5.88 in Agua Dulce (Locality 10; Tenerife), and 12.73 in Ajuy (Locality 21; Fuerteventura), and the overall average number of species per survey was 7.92. Species diversity (H') was low
Mean 1 0.100 0.003 0.005 8.344 0.306 1.819 0.048 0.012 0.022 0.105 3.911 0.913 0.022 0.051 3.466 1.733 16.083 3.292 0.001 0.233 0.001 0.005 0.005 0.045 0.008 0.006 0.285 0.051 0.010 3.778 0.911 0.429 0.268 0.254 0.027 0.370 28.870 0.001 0.112 0.088 0.008 0.006 0.008 17.071 7.92 270.44 0.53
(SD)
Max.
%Occur.
Mean 2
Av size
(0.36) (0.05) (0.07) (57.80) (1.10) (43.71) (0.26) (0.13) (0.22)
3 1 1 850 11 1050 3 2 4
8.31 0.34 0.52 9.70 15.07 0.17 3.81 0.86 1.38
1.20 1.00 1.00 85.98 2.03 105.00 1.27 1.40 1.62
26.15 42.50 73.33 15.81 11.41 15.00 26.07 20.00 6.07
(1.22) (59.39) (10.94) (0.18) (1.24) (58.82) (41.63) (117.53) (29.53) (0.04) (0.62) (0.04) (0.07) (0.07) (0.71) (0.17) (0.13) (0.65) (0.28) (0.11) (5.58) (1.41) (5.49) (1.87) (0.74) (0.18) (0.70) (55.74) (0.04) (0.60) (0.35) (0.20) (0.10) (0.09) (113.45)
22 1000 250 3 30 1000 1000 1000 550 1 5 1 1 1 15 4 3 5 3 2 73 12 100 30 5 2 4 500 1 9 3 5 2 1 1000
1.73 1.73 5.54 1.73 0.17 0.34 0.17 2.42 3.98 0.17 16.63 0.17 0.51 0.51 0.86 0.34 0.34 20.45 3.64 0.86 73.31 45.23 2.07 5.54 13.34 2.42 27.38 94.10 0.17 5.89 6.93 0.17 0.51 0.86 3.12
6.10 225.70 16.46 1.30 30.00 100.00 100.00 662.85 82.60 1.00 1.40 1.00 1.00 1.00 5.20 2.50 2.00 1.39 1.42 1.20 5.15 2.01 20.66 4.84 1.90 1.14 1.35 30.67 1.00 1.91 1.27 5.00 1.33 1.00 547.22
14.59 16.78 20.24 35.38 70.00 17.50 15.00 19.97 15.36 20.00 8.62 10.00 13.00 61.66 39.42 50.00 65.00 16.63 11.16 18.33 15.71 10.07 13.34 18.12 12.13 22.50 18.20 7.07 ' 35.00 18.53 4.05 20.00 5.50 17.00 2.95
(2.73) (416.30) (0.19)
19 [-1] 4082 [3] 1.03 [01
throughout the study area: from 0.27 on Las Playitas (Locality 28) to 0.78 on Los Molinos (Locality 22), both on Fuerteventura. The number of individuals per survey and per locality varied considerably, with a minimum of 34.33 on Bahia de Arguineguin (Locality 16; Gran Canaria) and a maximum of 1312.20 on La Carrera (Locality 4; Tenerife). The overall average number of fish per survey was 270.44. A detailed study per species and per location (Table 2) revealed that, in general, those species economically important to the local fishing community (i.e., Diplodus spp., Mycteroperca rubra, Pseudolepidaplois scrofa, Serranus atricauda and Sparisoma cretense) were more abundant and the average length of fish per survey was
219 T a b l e 2 A v e r a g e a b u n d a n c e {numbers) a n d a v e r a g e total length (cm, in parentheses) of species at locations surveyed. L o c a t i o n s n u m b e r e d as in Fig. 1 ( - - not recorded) Species
L o c a t i o n No.: 1
Abudefdufluridus
2
50.88 (7.40) --
Apogon imberbis
3
4.63 (9.87) ----
--
Atherina presbyter
21.76 (7.49) 29.40 (2.58) 46.76 (5.99)
--
Aulostomus strigosus
4
--
Balistes c a r o l i n e n s i s
.
Boops boops
287.50 (13.04) --
Bothus podas
.
--
Canthigaster rostrara
1.88 (3.80) 0.88 (7.86) 270,00 (7.69)
Centrolabrus trutta Chromis limbatus
2.34 (5.55) 1.94 (10.66) 1.47 (10.32) 0.41 (13,46)
Coris julis -
-
Dasyatis pastinaca
--
Dentex gibbosus
--
-
--
0.03 (40.00) 0.59 (15.53)
--
Diplodus cervinus
0.50 (13.75)
Diplodus puntazzo
.
Diplodus sargus
-
.
5.00 (15,03} 1.34 (13.14)
Diplodus vulgaris -
Echiichthys v i p e r a
0.20 (13.89) 0,06 (10.63)
-
-
-
Epinephelus alexandrinus
.
Epinephelus 9uaza
.
. -
Heteroconger longissimus
.
.
-
.
-
-
.
Kyphosus sectator
--
~ --
.
-
Labrisomus nuchipinnis Lithognathus mormyrus
0.25 (10,00) --
M
u
g
i
l
i
d
a
e
(
u
n
i
d
e
n
t
i
f
Mugil c e p h a l u s
i
e
d
.
Mullus surmuletus
-
.
.
-
--
-
0.13 (18.75)
.
--
0.03 (8.00) .
. .
0.20 (20.00)
-
-
-
-
.
.
0.02 (15.00)
.
.
.
0.33 (16.67) 0.22 (3.00)
-
--
0.02 (11.25) 0.63 (13.32)
-
---
-
-
-.
-
.
-
-
-
-
-
--
(5o.oo}
.
0.06 (19.50) -
-
-
-
-
-
-
-
-
-
--
--
0.01 (10.00)
. .
0.17
-
-
.
.
.
0.33 (14.00)
0.01 (7.50)
0.03
-
.
.
--
-
-
-0.07 (15.00)
.
.
-
. .
-.
.
0.13 (5,00)
--
(20.00) -
--.
-
(50.00) . . . . 029
.
30.33 (20.82)
.
0.88
(50.00) . .
-
--
.
0.04 (12.86)
0.67
.
.
.
.
.
---
0.01 (10.00)
. .
0.06 (12.50)
.
.
.
.
)
.
.
-
0.67 (10.00)
.
. . 0.33 (5.33)
.
--
{35.oo)
-
.
.
20.00
.
-
.
0.50 (20.00)
-0.31 (11.00) 0.03
-
--
.
.
.
.
-
-
.
-
--
-
.
0.17 (70.00)
-
--
Heteropriacanthus cruentatus
.
.
--
.
-
-
--
--
.
.
.
3.50 (6.38) 6.00 (8.81) 2.67 (10,00) 0.33 (15.00)
23.09 (8.53) 0.95 (5.06) 0,91 (3.00) 0.09 (52.I4) 0.0I (20.00) 020 (19.46) 0.27 (12,71) 6.89 (5.13) 2.20 (10.28) 74.16 (9.04) 0.30 (7.62)
(8.00)
.
.
17.33 (8.82) 0.83 (7.00)
--0.13 (8.00) 7.38 (4.78) 0.38 (10.00) 10.38 (9.04)
0.44 (6.50) 4.56 (10.63) 1.89 (11.76) --
0.90 (10.00) 0,03 (10.00)
. .
.
.
10.22 (5.39)
.
.
.
0.03 (5.00)
2,33 (19.64)
-
.
0.12 (15,00) --
-
.
.
.
.
-
12
.
-
.
.
.
Gobius paganellus
-
0.67 (26.25)
.
.
.
11.88 (9.42) 0.25 (6.50) ---
11
.
66.18 18.97 (5.78) (10.91) 0,06 -(15.00) -9.94 7.52 (5.04) (5.16) 0,76 2.24 (9.92) (8.9i) 266,76 0.03 (9.23) (5.00) -0.03 -(5.00) -. . . . . . . . . 0.18 (13.33)
--
.
0.03 (70.00)
-
.
.
.
-
166.67 (15.00) --8.83 (5.55) --665.67 (8.72) --0.70 (40.00) . .
10
9
22.97 7.78 (8.17) (9.31) 0.41 -(4.50) -6.90 (5.00) . . . . . .
.
0.20 (9.00)
.
.
Enchetycore anatina
-0.33 (42.50) 0.17 (25.00)
-0.04 (10.00)
.
2.13 (20,59)
-
8
19.94 (7.15) 2,71 (5.98) --. .
.
54.33 (12.19) 0.33 (11.00) 4.20 (5,21) 1,20 (7.39) 210.20 (8.70) 0.07 (20,00)
-
7
17.50 (8.83) 0.33 (7.00) --. .
.
600.00 (15.00) 0.17 (10.00) 2.67 (5.56) --457.17 (9,78) --
0.01 {50.00)
6
48.27 (7.98) 63.47 (2.90) 146.67 (5.34) 0.07 (50.00)
.
11.24 (16.72) 0.23 (13.81) 6.07 (5.22) 1.26 (9.66) 41.74 (6.04) --
--
Gymnothorax unieolo~.
135.33 (8.58) 0.17 (5.00) --0.33 (50.00)
---
5
1.12 (19.21)
(30.00) 0.24 (19.29)
--
-
-
-
--
-
-
-
-
-
-
0.67 (18.09)
220
13
14
15
52.00 (8.28)
14.00 (8.94) --
15.00 10.33 (9.12) (7.60) 7.50 1.00 (7.67) (6.83) --
-
-
-
-
-6.00 (5.58)
39.17 (9.29) .
.
-
-
-
-
-
90.00 (15.00) 0.80 (13.75) 6.40 (4.66) 0.40 (11.00) 175.40 (9,20)
58.33 (15.00) -
-
.
.
0.67 (20.00) .
8.17 (17.96) 3.50 (14.05)
r
_
-
0,60 (40.00)
-
-
-
-
-
20
-
-
-
-
( 5 . 0 0 )
-
-
21
-
22
23
6.73 4,11 (7.86)(8.78) 0.18
-
--
-
-
-
-
-
-
.
.
-
-
-
-
-
-
-
-
-
-
-
(55.00)
---
.
---
.
.
( 3 . 0 0 )
.
----
I4.17 -(17.65) 0.67 1.67 0.67 (9.50) (9.20) (20.00)
-
-
-
-
-
-
-
.
-
-
2.50 (10.00)
-
.
.
26
27
-
-
-
-
-
-
-
-
-
-
28
-
-
( 5 . 0 0 )
-
-
-
-
-
--
-
-
-
.
.
.
.
.
.
.
.
.
.
.
.
2.17 0.63 0.83 (26.15) (23.00) (22.00) 0.13 0.17 (20.00) (25.00) 21.17 2.25 8,17 (15.35) (14.72) (17.86) 2,83 4.63 2.33 (16.47)(17.70)(18.57)
---
-
-
- -
-
0.13 (10.00)
-
- -
-
-
0.29 (17.50)
---
-
.
.
.
.
-
.
.
.
.
0.71 (15.00) 1.00 (16.43)
-
----
-
-
0.69 0.67 0.50 (15.45) (20.00)(28.75)
-
-
-
-
-
.
-
-
-
-
-
.
.
.
.
.
.
0.09 (45.00) 0.09 (5.00)
.
.
0.09
.
(80.00)
.
-
-
--
-
0.t7 (70,00) -
-
-
--
0.17 (40,00) -
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
.
0
.
.
----
2.38 1.50 0.38 (18.42) (20.56)(23.33) 0.83 0,69 4.25 7.00 (9.00)(20.00) (19.22)(19.82)
.
-
-
0.33 (15.00)
.
.
.
.
.
-
-
-
-
-
-
-
-
.
-
-
-
-
-
--
-
-
-
-
-
-
-
-
.
.
0.27 0.78 (10.00) (13.57)
--
0.67 1.91 3.89 (20.00) (19.76)(5.43)
-
-
.
0
6
(5.00)
0.13 (15.00)
.
.
-
-
-
-
-
-
-
-
-
-
-
-
-
-
0.17
(10.00)
0.14 0.50 0.33 (15.00) (20.00) (12.50) 0:33 (40:00) -
- -
1.67 - (20.00)-
0
.
-
--
-
-
--
-
--
--
-
-
-
-
-
-
-
-
-
-
9.50 (25.00)
0.t7 (25.00}
-
.
0
(5.00)
. .
0.14 (25,00)
-
-2
-
-
-
-
0.20 (20.00)
( 9 . 0 0 )
1.00
.
0,33 (27.50)
-
--
.
.
7,00 (22.74)
-
.
.
.
-
--
.
-
16.17 3.75 (9.21)(8.57) 0.33 (6.25) --
-
.
-
32
1,17 1.25 1.17 1.00 4.57 2.00 2.67 1.31 1.67 0.63 (5.00) (5.80) (5.00)(10.00) (3.72) (3.13) (3.38) (5.57) (6.75) (6.00) 0.00 0.88 0.33 2.00 0.50 0.13 0.63 (0.00) (9.00) (12.50) (12.50) -(11.67)(12.50) -(12.00) 204.00 31.13 11.00 3.00 438.57 416.25 59.83 71.00 134.08 22.00 (5.10) (7.99) (7.80) (6.67) (7.09) (7.87) (6.71) (9.94) (10.31) (9.68) 0.83 0.25 0.33 11.71 3.75 4.17 0.17 3.00 (7.80) (10.00) (15.00) (15.00) (2.96) (3.00) (4.88) (20.00)(19.17)
.
-
31
.
.
-
30
.
.
-
-
2.75 (15.45)
-
.
-
29
14.29 27.00 17.00 15.69 (8.94)(8.15)(7.16)(8.90) 0.29 0.33 0.38 (5.00) (5.00) (6.33) 8.33 9.38
.
0.17 1.73 1.00 (20,00) (26.58)(17.78) 0,27 (20.00) 1.83 11.09 26.00 (13,64) (16.27)(12.76) -13.45 i0.1I -(15,03}(12.03)
--
.
.
23.50 (20.99) 0.50 (20.00)
0,17 (20.00)
-
-
25
2.13 1.83 3.00 (9.41)(9.09)(10.00) 0.13 -(5.00) ---
166.67
-
-
-
-
2.00 (23.75)
-
-
24
10,83 (5,77) --
(5.00)
-
-
.
.
_
-
( 5 . 0 0 )
.
.
17.80 (17,53) 1.60 (21.25)
19
20.33 17.00 33.50 23.50 (9.63) (9.35) (9,12)(8.67) -0.17 0,17 -(8.00) (8.00) 16.67 - 208.33 --
-
-
1.40 (19.29) .
18
8.33 85.33 75.00 222.82 6.78 (10.00)(10.12) (9.67) (12.25)(10.00) 0.33 0.17 (9.50) (15.oo) . . . 5.17 3.50 12.00 6.00 0.09 0.11 (4.61) (3.95) (4.68) (3.97) (5.00) (5.00) 2.00 0.83 1.64 1.33 -(11.92)(10.60) -(7.39) (9,17) 289,67 3.50 139.33122.83 110.67 209.33 5.09 0.33 (8.82) (7,86) (8.97) (9.08) (9.89) (7.31) (5.63)(11.67) 0.50 0.64 1.33 (18,33) - (8.86)(13.75) 0.33
.
.
17
33.33 -(15.00) 0.17 (10.00) -3.83 0.50 (4.26) (5.33)
.
.
16
0,25 (20.00)
-
-
-
-
2.00 (20.00)
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
- -
1.33 0.31 0.33 (5.63)(20.00) (15.00)
- -
-
-
-
-
(continued overleaf)
221
Table
2 (continued)
Species
Location
No.:
1
2
M u r a e n a augusti
3
4
--
0.01
--
M y c t e r o p e r c a rubra
(65.00)
0.25
0.19
(37.50)
M y l i o b a t i s aquila
0.12
(27.50)
0.13
.
Oblada melanura Ophioblennius atlanticus Pagellus acarne Pagrus auriga
--
6.67
--
--
--
(15.00)
--
0.37
0.50
1.87
--
0.06
0.14
0.11
--
(11.50)
--
. --
--
--
0.04
--
--
--
--
.
.
(10.00) 0.01
Sarda sarda
.
.
Sardina pilchardus
.
.
.
--
--
--
--
--
Scorpaena maderensis
0.38
Scorpaena n o m t a
--
6.07
--
--
(8.96)
--
.
.
.
.
.
.
.
.
Seriolafasciata
--
--
--
--
(37.78)
--
--
-.
--
.
.
.
.
--
Sparisoma cretense
-
3.75 (16.30)
0.50
.
0.03
.
(18.38)
--
0.07
.
.
(16.73)
(20.00)
10.34
.
(13.33)
---
--
.
.
.
-.
.
0.14
--
0.25
(8.25)
--
(8.00)
0.17 (15.00)
.
10.00 0.01
.
. .
0.33
(13.95)
.
.
.
(22.00)
.
0.03
--
0.38
--
(15.00)
--
(13.33)
--
(16.67)
--
--
--
--
--
--
0.03
.
. .
0.17 (15.00)
--
.
.
(10.00)
.
.
. .
.
0.29
(20.00)
.
(20.00)
--
.
(14.09)
.
.
.
2.53
.
.
.
.
.
1.83
.
.
0.88
.
.
.
(41.67) .
0.34 (8.61) 0.01
.
.
.
.
2.82
35.98
--
.
(50.00)
(16.11)
.
(20.00) 2.25
--
--
.
.
--
--
.
.
0.60
(16.67)
. .
--
--
.
.
--
.
0.34 (16.07)
(15.00)
.
--
0.18
.
.
.
--
12.20
0.06
.
.
.
34.48
(14.67)
.
0.14 (19.57)
(20.00)
(10.00)
--
.
0.17
.
0.07
--
(8.60)
6.10
.
.
.
--
. .
.
. .
.
.
(6.00)
. .
0.83
--
.
.
0.35
.
0.07
--
.
(10.00)
.
(10.00)
.
.
.
Serranus atricauda
--
.
.
.
--
.
Scorpaena scrofa
.
42.00
0.17
.
--
(17.50)
.
(10.40)
.
. .
.
.
--
(10.00)
.
.
Seriola s p .
.
.
. .
. .
0.18 (15.00)
.
--
.
0.31
.
Seriola rivolana
.
.
.
--
.
.
.
.
. .
--
-.
(11.88)
.
.
(i5.00)
--
.
0.28
.
.
. .
(7.45)
.
.
0.03
(15.00)
.
--
.
.
.
.
.
0.74
.
Scorpaena porcus
. .
.
(10.00)
0.12
.
-.
0.01
.
.
.
.
.
(15.00)
.
.
(10.00)
0.22
.
.
.
(10.00)
.
--
.
.
.
0.03
(6.67)
--
--
0.21
.
.
0.10 (8.25)
.
--
.
--
(10.00)
.
166.67
.
(20.00)
--
.
.
--
.
.
0.03
.
.
--
.
--
.
--
.
.
.
0.13
.
.
.
.
(10.00)
.
.
.
.
.
.
.
.
.
.
.
--
.
.
.
--
.
.
--
0.17
--
(15.00)
(20.00)
0.83
(13.10)
(10.00)
175.00
--
--
7.09
.
(6.25)
(19.00)
.
0.19
.
(10.00)
(80.00)
(30.00)
(14.17)
Pseudolepidaplois scrofa
0.33
.
.
--
--
.
.
--
.
.
.
.
--
(13.33)
.
.
(9.23)
(i9.07)
Sciaena umbra
.
.
15.29
1.84
Sarpa salpa
.
--
(9.82)
.
.
.
.
(28.57)
--
.
.
.
--
5.80
Pseudocaranx dentex
Sardinella maderensis
.
0.04
--
.
.
--
(5.11)
--
.
.
.
--
--
--
Sardinella aurita
. .
---
--
(10.68)
Serranus scriba
. . .
0.06 (15.00)
--
--
P o m a d a s y s incisus
0.17 (60.00)
0.02 (56.67)
--
(15.00)
--
.
11.28
--
Parapristipoma octolineatum
.
.
(19.68)
Pagrus pagrus Parablennius pilicornis
.
.
.
0.16
.
.
.
12
.
4.00 (15.00)
.
.
11
(75.00) 3.63 (18.97)
.
0.13
10
9
.
.
0.01
8
.
(6.00)
.
7
. --
.
M y r i c h t h y s pardalis
6
.
(18.44)
(50.00)
Serranus cabrilla
5
. .
. .
1.47
1.21
(12.80)
(13.54)
0.04
.
.
13.00
1.25
(13.63)
(7.50)
6.50 (12.41)
4.93 (11.52)
222
13
14
--
15
--
0.33
--
-
--
i6
17
18
19
--
--
0.17
--
--
--
0.17
.
--
(60.00)
--
--
--
(80.00)
.
--
--
0.33
--
--
--
--
--
--
--
--
(25.00)
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
. .
--
--
-
.
1.60 (16.25)
1.33
.
(12.50)
.
.
.
. .
.
.
.
.
.
.
.
.
.
.
.
.
.
.
--
167.67
--
--
--
(19.99)
--
41.67 --
.
--
.
.
. .
.
. .
. .
.
.
.
.
.
--
2.09
.
(14.78)
.
.
.
.
.
.
.
(17.50) .
. .
(15.00)
(33.64)
.
--
--
--
--
.
(38.75)
.
.
.
.
0.38
.
.
. .
.
.
0.25
(10.00)
--
(53.33)
--
--
--
.
.
.
.
.
.
.
.
.
2.57
.
. .
(23.33) .
.
0.38
(13.00)
.
. .
. .
.
.
.
(15.88)
0.42
0.06 (70.00)
.
.
.
(25.00)
0.67
.
.
.
---
.
.
. 1.83
.
. .
. 0.11
(34.29)
.
(15.56) 0.19
(17.50)
.
.
56.25
(12.11)
(11.67)
.
. .
.
.
.
.
--
.
3.17
--
0.29
--
.
185.63
(17.40)
.
.
.
119.58
.
.
.
--
.
.
.
0.64
. .
.
.
--
.
(15.00)
.
--
(15.00)
.
0.17
0.13
(35.00)
.
.
(15.00)
0.50
--
.
.
0.43
.
.
0.25
.
.
.
2.00
.
.
--
.
(20.00)
.
(15.42)
. .
. .
--
.
(10.00)
.
--
(15.00)
.
.
32
.
. .
31
.
--
.
6.00
30
0.33
. .
.
. .
.
.
.
29
. .
--
. .
.
.
.
.
(17.95)
(11.25)
.
.
.
28
.
--
.
0.67
0.11
. .
.
.
--
27
. .
2.75
.
--
.
.
0.33
.
.
.
(8.33)
(18.75)
.
.
0.18
.
.
.
0.91
--
.
.
(7.50)
(35.00)
1.33
.
.
(5.40)
(14.38)
.
. .
.
4.00
--
.
.
.
--
(25.00)
(11.25)
.
.
--
(13.00)
.
. .
.
(15.00)
0.17
0.22
26
.
0.38
(35.00)
(6.60)
0.36
.
.
. .
1.67
25
(28.33)
I].44
(11.50)
--
.
. .
0.91
0.33
.
.
. .
.
(10.00)
. .
(70.00)
--
0.50 (40.00)
.
.
0.33
.
.
.
.
0.11 (35.00)
0.09
.
--
0.27 (31.67)
.
2.50
(10.00)
.
.
.
0.17
.
.
.
(20.00)
--
-
24
--
.
(15.00)
23
--
.
.
22
--
0.40
0.33
2t
(60.00)
(27.50)
.
20
.
.
--
.
.
0.31
.
(32.00)
.
4.29
.
(70.00)
.
.
.
.
. .
0.17 (27.50)
0.25 (45.00)
. .
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
148.75
--
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
(19.89)
--
--
19.38
--
25.00
(22.42)
--
(25.00)
.
.
.
.
.
.
.
.
21.82
.
.
.
.
.
.
.
.
(16.67)
--
-
.
--
--
--
--
.
.
--
.
.
.
.
.
.
.
.
.
.
.
.
. .
--
-
-
-
. . 2.50 (23.00)
.
.
.
.
.
4.00
.
. .
.
.
.
.
--
--
--
--
.
.
3.67
--
--
--
0.50
.
2.50 (13.67)
0.50 (18.33)
--
--
.
.
.
.
.
.
.
.
4.33
.
.
.
.
0.67 (18.75) 0.33 (17.50)
.
. .
2.83 (15.88)
--
--
.
.
.
. .
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
. .
. .
(45.00)
--
--
(16.67)
--
--
--
--
--
--
--
1.00
1.43
--
--
--
--
(5.00)
(8.50)
--
0.17
0.17
-4.33 (21.54)
-4.00 (22.28)
(20.00) 7.33 (23.64)
0.29 (20.00)
1.50
2.83
1.13
1.50
0.38
(14.17)
(10.88)
(18.33)
(19.17)
(18.33)
--
(10.00)
0.67
0.38
.
.
.
.
.
.
.
.
.
.
.
.
---
--
.
--
(10.00)
0.13
(25.00)
.
(1722)
14.67
0.08
0.67
.
0.25 (10.00)
.
(50.00)
--
(24.32)
0.08 (10.00)
(30.00)
--
6.55
.
.
--
(23.61)
--
.
1.00
8.00
--
.
--
(15.23)
0.67 (8.75)
.
.
0.82
--
(10.00)
0.13
.
. .
--
0.17
.
.
(15.00) 6.33
.
.
. .
--
.
.
.
--
.
.
.
0.09
(17.82)
. .
. .
.
(12.69)
. .
.
.
(15.56)
.
.
.
3.00
.
.
. .
(10.00)
0.17
. .
--
(18.33)
.
(23.41)
.
(65.00) --
(14.44)
(9.00)
.
0.67
0.33
--
0.17
.
.
.
11.25
(25.00)
. .
.
--
0.17
(10.00)
.
. .
.
.
0.11
(10.00)
.
.
.
(10.00)
0.27
.
.
.
(25.25)
.
(20.00)
0.20
.
.
(20.00)
(10.00) .
.
.
0.17
(20.00)
.
-.
.
.
.
.
0.20
--
. .
.
.
.
.
.
. .
.
.
.
.
.
--
. .
-.
.
--
.
0.33 (15.00)
0.56
--
0.43 (16.67)
1.00 (17.50)
6.17 (11.57)
(12.50)
0.08 (10.00)
--0.38 (18.33)
0.75 (28.75)
3.25
1.13
(30.00)
(23.89)
(continued
overleaf)
223 Table 2 (continued)
Species
Location No.: 1
2
Sphoeroides spengleri
3
0.53 (10.94) --
Sphyraena viridensis Spondyliosoma cantharus
3.75 (20.00)
Stephanolepis hispidus Synodus saurus Synodus synodus Thalassoma pavo
116.38 (7.86) ---
Torpedo marmorata
-
4
1.87 (9.98) 0.40 (17.27)
5
0.17 (10.00)
0.40 (4.17) 0.07 (70.00) 0.13 (5.00) --0.07 (10.00) 0,87 (16.15) 108.40 (5.11) --
--
-
-0.09 (18.33) --0.03 (25.00) 8.16 (10.01) ---
-
-
0.88 (11.82) 0.02 (23.33) 0.49 (18.20) 22.07 (7.62) 0.01 (35.00)
Trachinus draco
-
6
-
0.83 (12.00) -0.17 (20.00) 78,67 (7.92) ----
----
0,25 (5.00)
0,16 (3.80)
-
-
-
-
-
8
0.94 (10.00) 4.47 (15.00) 0.53 (17.78) 0.53 (11.67) 0.12 (20.00) 0.53 {22.78) 19.06 (7.12) 0.18 (16.67) --
--
---
1.83 (9.91) ----
--
Tripterygion delaisi
7
--
10
9
1.45 (7.48) 0.03 (40.00) -
0.67 (13.33) 1.22 (14.09) --
4.38 (10.71) ---
-
-
-0.03 (30.00) 0.59 (14.12) 29.34 (7.75)
-
----
0.07
-
-
-
-
-
-
-
12
--16.67
0.62 (10.72) -
-
(7.00)
--
0.16
--
(12.96) 0.04
-(15.00) 0.17 0.04 (25.00) (23.57) 0.17 0.40 (20.00) (19.46) 81.00 25.82 (7.70) (6.14) 0.37 -(18.50) -0.12
-
0,75 (20.83) 5.25 (7.10) --
74.00 (7.32) ----
(22.50)
11
--
--
(4.00)
0,04 (4.60)
Umbrina canariensis Vanneaugobius canariensis
0.01
(5.oo) Xyrichthys novacula
--
--
0.02 (18.33) 40.81 (3.27)
Unidentified larvae
0.12 (6.00)
--
-0.17 (15.00)
--
. --
-
-
.
--
. .
.
.
. .
-
16.67
. 70.59
24.14
(2.00)
(3.13)
(2.00)
.
.
. -
-
---
0.17 (15,00) 216,67
--
(2.04)
--
-
-
Table 3 Summary [means (SD)] offish community and environmental parameters associated with locations during sampling period. Locations numbered as
in Fig. 1 Parameter
Location No.: 1
No. of species No, of individuals Av size Species diversity(H') Depth (m) Substrate slope Substrate type % sand % algae Algal height No. of sea urchins No. of samples
2
8.88 8.56 (1.55) (2.68) 746.50 50.53 (447.67) (83.47)
3
4
5
6
7
8
9
7.11 10.67 9.53 6.33 8.12 6.28 6.67 (2.32) (1.86) (3.07) (1.51) (2.55) (2.20) (1.73) 230.50 1312.20 698.73 1242.50 484.76 162.90 114.78 (377.86) (410.00)(681.50) (1569.90)(583.21) (307.42) (157.92)
10
11
12
5.88 8.00 7.33 (1.64) (2.10) (2.20) 42,75 361.17 198.69 (39.94) (369.75) (289.65)
13
14
15
8.50 12.40 12.50 (1.05) (2.41) (2.51) 228.17 528.60 576.17 (90.66) (522.88) (432.88)
10.04 (2.05) 0.46 (0.i0)
11.85 (2.33) 0.73 (0.16)
8.79 (3.44) 0,53 (0.19)
12.48 (1.09) 0.48 (0,10)
7.78 (1.73) 0.52 (0.10)
10,15 (4.65) 0.36 (0.15)
7.94 (2.47) 0.37 (0.19)
8.20 (2.53) 0.49 (0.12)
9.88 (2.31) 0.57 (0.22)
8.77 (1.28) 0.60 (0.10)
6.87 (3.07) 0.47 (0,21)
9.06 (2.65) 0.54 (0.18)
13.15 (4.52) 0.47 (0.13)
10.94 (3.38) 0.59 (0.21)
11.64 (3,75) 0.37 (0.16)
9.38 (0.96)
8.56 (0.44)
6.49 (0.84)
13.32 (0.37)
5.90 (0.61)
15.84 (2.82)
10.00 (1.44)
4.23 (0.45)
2.49 (0.17)
9.94 (1.67)
4.75 (0.36)
6.92 (0.86)
10.92 (0.84)
14.79 (1.73)
14.33 (0.16)
1.60 1.00 1.00 (0.68) (0.00) (0.00) 1.93 2.33 2.93 (0.88) (0.82) (0.96) 10.66 15.83 15.67 (10.50) (10.21) (16.68) 52.39 0.00 28.00 (36.57) (0,00) (41.09) 10.51 0.00 7,00 (10.10) (0.00) (10.66) 109.26 833.33 275.33 (187.08) (186.19)(260.37)
2.33 (0.82) 2.17 (0.41) 24.17 (22.00) 0,00 (0.00) 0.00 (0.00) 283.33 (116.90)
1.22 1.13 (0.44) (0.35) 2.89 1.75 (0.93) (0,89) 1.11 6.88 (3.33) (7.53) 87,22 50.00 (22.52) (39.28) 33.33 10.00 (8.66) (6.55) 0.44 100.13 (1.01) (192.65)
1.00 (0.00) 2.00 (0.00) 20.00 (24.49) 58.33 (21.37) 26.67 (5,16) 3.00 (4.69)
1.36 3.00 (0,69) (0.00) 1.99 1.83 (0.83) (0.98) 6.10 22.50 (11.02) (23.18) 66.39 50.00 (31.69) (46.58) 12.98 6.67 (8.41) (6,06) 45.38 100.00 (72.69) (126.49)
2,00 (0.71) 2.80 (0.84) 23.00 (24.90) 25.00 (35.36) 5.00 (7.07) 74.00 (55.95)
1.17 (0.41) 2.17 (0.41) I0.00 (7.07) 6.67 (16.33) 1.67 (4.08) 49.50 33.61
1.00 1,25 (0.00) (0.51) 3,13 2.72 (0,35) (0.63) 2.50 2.66 (7.07) (5.68) 36.88 67.19 (42.34) (23.28) 5.63 5.94 (6.23) (3.69) 223.25 0.53 (234.43) (1.14) 8
32
136
6
15
6
2.00 1.69 (0.79) (0.47) 2.7i 1.83 (1.16) (0.47) 8.24 5.34 (12.98) (7.55) 40.88 43.45 (35.94) (43.51) 8.18 9.14 (6.04) (9.92) 48.29 100.21 (83.85) (111.97) 17
29
9
8
6
164
6
5
6
224 Table 2 (continued)
13
14
0.67 (11.25)
15
i6
.
--
0.60 (10.00) -. 4.20 (19.76) 0.20
--
(I0.00)
(I 1.00)
. 10.00 (19.25)
0.50
1.00 (20.00) 0.33
.
.
.
.
.
.
.
.
--
(11.67) 3.33 (11.50)
. . --
. .
. . --
Table
0.33
16 6.00 (2.00) 34.33 (30.43)
.
.
.
22
23
0.82 0.33 (10.56) (10.00) 0.27 . (60.00) .
--.
.
.
21
.
.
0.83
. . 1.00 (4.17) . . . --
.
. .
.
. -.
.
.
.
0.17
. --
--
.
. . 0.17 (5.00)
.
.
. .
. .
.
.
. .
.
--
.
31
32
.
.
.
.
.
.
.
.
.
.
.
.
.
0.08
--
. . . . . (15.00) - 8.33 4.00 8.29 7.50 155.17 7.88 63.75 6.38 (6.40) (6.25) (5.91) (5.70) (5.74)(10.81) (9.86)(10.00)
. .
.
.
0.38
.
.
.
.
(23.33) 14.t3 (9.05)
. .
.
.
.
30
0.17 0.38 0.25 0.38 (5.00) (12.50) (11.67) (10.00) . .
(20.00)
.
.
.
.
29
0.43 0.50 (8.33) (12.50) . . . .
1.00
0.33 0.33 --(3.00) (5.00) -0.36 -0.13 (4.50) - -(5.00) . . . . . . . . . . . . . . . . . . .
--.
.
. --
0.17
28
.
--
.
.
.
. .
27
.
.
.
.
26
.
.
.
.
.
. .
--
.
((15.00) .
.
.
. -. .
.
.
.
.
1.50
. .
25
0.17
.
. . ---
24
.
.
0.83
. .
.
3.00 -(3.00) - -0.14 -(3.00)
-----
. .
. .
(continued)
17
18
19
20
21
9.17 7.83 9.83 7.00 12.73 (0.98) (0.75) (4.07) (1.41) (4.47) 218.00 261.00 479.50 278.33 315.91 (177.14) (252.58) (527.75) (168.59) (366.70)
9.76 (1.1t) 0.58 (0.10)
9.08 (1.41) 0.49 (0.16)
9.32 (0.72) 0.49 (0.15)
6.98 (0.17) 1.00 (0.00) 1.17 (0.41) 0.00 (0.00) 93.33 (16.33) 5.00 (0.00) 20.00 (29.83)
8.75 (0.69) 2.83 (0.41) 2.33 (0.52) 3.33 (5.16) 78.33 (38.69) 7.50 (4.18) 9.17 (20.10)
8.07 (0.28) 2.33 (0.52) 2.50 (0.84) 1.67 (4.08) 90.00 (6.32) 10.00 (0.00) 2.83 (4.02)
6
20
0.17 (10.00) 0.17 (75.00)
0.17 (20.00)
. .
.
200.00 (3.00)
3
.
. .
--
--
----
.
--.
1.00 (20.00) .
--
.
19
(26.00) (15.00) (17,00) (17.00) (12.22) (10.00) -(15.00) 7.50 12.83 11.00 22.17 15.67 25.83 13.27 19.89 111.83 (6.42) (9.87) (9.65) (7.71) (9.96) (8.95) (5.95) (8.53) (6.68)
- -
.
18
.
0.83
-7.60 (8.42)
- -
1.67 (12.50) -.
--
17
6
6
22
23
24
25
t0.44 (2.24) 104.00 (64.08)
11.50 8.88 (3.21) (2.59) 532.17 79.75 (479.52)(70.67)
8.33 (2.25) 52.00 (31.56)
7.86 (0.56) 0.42 (0.11)
11.81 (2.84) 0.58 (0.23)
11.21 (4.21) 0.78 (0.08)
7.62 11.83 (2.54) (2.49) 0.52 0.67 (0.16) (0.14)
15.09 (2.63) 0.79 (0.10)
1 8 . 0 1 11.51 (0.19) (0.69) 1.00 1.67 (0.00) (0.52) 2.67 3.00 (1.51) (1.10) 9.17 2.50 (4.92) (6.12) 0.00 14.17 (0.00) (34.70) 0.00 1.67 (0.00) (4.08) 350.00 158.33 (31.62) (86.12)
9.35 (0.99) 1.18 (0.40) 2.91 (0.94) 0.91 (3.02) 91.82 (8.74) 5.00 (0.00) 1.09 (2.98)
6.16 (0.26) 1.44 (0.73) 2,11 (1.05) 8.33 (10.61) 62.22 (23.86) 6.11 (2.20) 0.11 (0.33)
16.33 6.36 (t.20) (0.46) 1.00 1.50 (0.00) (0.53) 2.83 1.88 (1.47) (0.99) 16.67 7.50 (22.51) (6.55) 37.50 82.50 (23.61)(12.82) 4.17 8.75 (2.04) (2.31) 116.67 20.00 (123.88)(23.42)
7.74 (0.45) 1.17 (0.41) 3.17 (1.17) 11.67 (6.83) 51.67 (18.35) 9.17 (2.04) 20.00 (10.49)
8.54 (1.54) 0.49 (0.19)
6
6
11
9
6
8
6
26 11.00 23.00 9.09 0.99 4.98 1.00 1.00 40.00 20.00 5.00 20.00 1
27
28
29
30
31
32
9.14 6.50 10.50 8.44 9.25 9.63 (2.04) (1.73) (4.09) (2.99) (2.22) (1.30) 490.29 462.75 265.33 337.69 349.17 258.38 (458.57) (286.09) (180.38) (418.08) (228.11) (257.39} 9.17 (4.20) 0.35 (0.21)
8.09 (0.47) 0.27 (0.22)
6.72 (0.60) 2.00 (0.82) 2.00 (0.00) 11.43 (10.69) 0.00 (0.00) 0.00 (0.00) 141,43 (72.44)
7.74 (0.80) 1.25 (0.50) 2.00 (0.00) 10.00 (0.00) 0.00 (0.00) 0.00 (0.00) 132.50 (53.77)
7
4
7.00 (2.16) 0.57 (0.16)
13.71 (3.87) 0.45 (0.15)
4.00 8.43 (0.19) (0.70) 1.i7 1.25 (0.41) (0.45) 1.83 2,13 (0.41) (0.89) 8.13 13.33 (12.11) (9.64) 81.67 10.94 (22.29) (23.61) 10.83 2.19 (2.04) (2.56) 15.50 146.25 (18.26)(126.25) 6
16
12.43 (2.41) 0.40 (0.15)
14.28 (4.28) 0.49 (0.27)
10.76 13.38 (0.62) (0.51) 2.08 1.25 (0.67) (0.46) 2.25 2.50 (0.62) (0.93) 9.17 19.38 (15.79) (21.45) 1.25 44.38 (3.11) (25.56) 0.83 8.00 (1.95) (6.02) 177.92 107.50 (97.03)(114.86) 12
8
225 greater at locations around Alegranza and Fuerteventura, whereas these species were not recorded or were present at the smallest abundances or sizes at the localities around Gran Canaria and Tenerife. Linear models Stepwise, multiple linear-regression models were constructed to predict variation (R 2) in the dependent variables (number of individuals, number of species, average size and species diversity) according to 13 independent variables [date, time of day, depth, slope, substratum, percentage of sand, percentage of algae, algal height, number of urchins and island effect (four islands)]; each represented as "dummy" variables). The variables were considered significant in the model at a level of p = 0.15. The amount of variation in the dependent variables explained by the independent variables was generally low. Only 28.36% of the variation of the number of individuals by sample could be explained using five significant variables (depth, substratum, percentage of sand, algal height and number of urchins). In regard to the number of species per survey, seven significant independent variables were identified (depth, slope, substratum, algal height and three islands) that explained a total of 38.83 % of the variation in this dependent variable. Only five independent variables (i.e., percentage of sand, percentage of algae, number of urchins, and two islands) could be identified as significant in explaining 14.58 % of the variation in fish length among the surveys. Finally, six variables (percent sand, percent algae, number of urchins, and three islands) were identified as significant contributors to only 8.89% of the variation in species diversity among the surveys. An ANOVA model was used to explain the variation in the number of individuals and species (both log-transformed), average fish length, and species diversity per survey using the islands only as independent variable. The island effect was a significant contributor to the variation in these dependent variables. Moreover, Tukey's Studentized range (post-hoc) test indicated that there were significant differences between islands for each of the dependent variables (Table 4). In general, the most important differences between islands, with regard to the overall dependent variables, were between those islands that are more distant (i.e., Alegranza and Tenerife); apparently there is a trend to increasing difference along an axis from east to west.
abundance or density) and the surveys in which they are observed. DCA orders both the species and the samples so that similar entities are near and dissimilar entities are more widely separated in a two-dimensional display (Gauch 1982). We have used this technique to establish patterns among species relative to their abundance within surveys at each of the 32 localities. We have also used this technique to determine patterns among the 32 localities with regard to species abundance at each.
Species The eigenvalues attributable to each of the first four axes were; Axis 1 =50.60; Axis 2 = 2 9 . 1 5 ; Axis 3 = 16.04; Axis 4 = 9.73. In Fig. 2, the contributing scores for the 76 species are displayed for Axes 1 and 2. Superficially, it is difficult to differentiate clear trends among the species affinities according to these two axes. In general, however, species to the right of Axis 1 are benthic species associated with hard substratum (e.g. Centrolabrus trutta, Diplodus cervinus, D. sargus,
D. vutgaris, Mycteroperca rubra, Serranus atricauda, Thalassoma pavo, etc.). In contrast, the species situated to the middle left are principally species that live in sandy bottoms (e.g. Bothus podas, Heteroconger longissimus and Xyrichthys novacuIa), or species that frequent areas transitional between rock and sand (e.g. Dasyatis
pastinaca, Lythognathus mormyrus, Mullus surmuletus, Pageltus acarne, Stephanolepis hispidus, Synodus synodus, etc.). Both epibenthic and pelagic, schooling species (e.g., Boops boops, Kyphosus sectator, Sardina pilchardus, Sardinella aurita, S. maderensis, Seriola sp., Spondyliosoma cantharus, etc.) have less affinity with the substrate and appear on both sides of Axis 1. To explain the arrangement of species along Axis 2 is considerably more difficult. One group occupies the mid-to-lower portion of Axis 2. This is a group of species which were generally abundant and were found one to several metres above the substrate. These species were typically found in large and compact or smaller, loosely aggregate schools (e.g. Abudefdufluridus, Boops
boops, Chromis limbatus, Pagellus acarne, Pomadasys incisus, Sardinella maderensis, Thalassoma pavo, etc.). Superficially, this is similar to the arrangement of species along the second DCA axis found by Bortone et al. (1991) on E1 Hierro. There are, however, numerous exceptions to this generalization. We believe that the order along Axis 2 could result from the interaction of diverse variables, which could mask a simple explanation of this complex data set.
Detrended correspondence analysis (DCA)
Localities Detrended correspondence analysis is a multivariate ordination technique that allows the detection of relations or patterns between species (using their relative
In Fig. 3, the values of the first and second axis are shown for the 32 localities. Along the right side of
226 Table 4 Summary of results of Tukey's Studentized range test between islands (A Alegranza; F Fuerteventura; G Gran Canaria; T Tenerife) for each dependent variable (log ind. logarithm of number of individuals; log spp. logarithm of number of species; A v size = average size; H' species diversity; * significant difference at P = 0.05) Islands
250 +26
~,~ 27
200
Dependent variable
23
+ 10[~
log ind.
log spp.
Av size
-0.05 0.00 0.09* 0.05 0.14" 0.09*
2.90* 3.39* 4.31" 0.49 1.41" 0.92
H'
5D
150
A F A G A-T F-G F-T G-T
0.18 0.04 0.30* -0.14 0.12 0.26*
F-test p
5.88 0.0006
20.01 0.0001
-0.15" -0.04 -0.09* 0.11" 0.06 -0.05
23.81 0.0001
5.71 0.0007
[]12
3O
z5~5 13
r
18A
< 10(
A
2D +25
D7
3~
9[3
D1
4~
~2
8[3
5(
A]egranza
~14 21~L
@
Fuerteventura
[]
Tenerife
Gran
500 ~22
400
46.
58
300 12~ ,32
60 ~5,20,47,48,53 29~ 11 " J1 63~ ~59 ~19,51
66 w"28 !~4
68
9~ 200
